WO2004025637A1

WO2004025637A1 - Skew detection method, optical pickup, and optical disc device

Info

Publication number: WO2004025637A1
Application number: PCT/JP2003/011742
Authority: WO
Inventors: Toru Nagara; Kyosuke Miyano
Original assignee: Sony Corporation
Priority date: 2002-09-13
Filing date: 2003-09-12
Publication date: 2004-03-25
Also published as: KR20050035515A; TWI260614B; US7218580B2; KR101053375B1; TW200423106A; JP4513570B2; JPWO2004025637A1; US20040264313A1

Abstract

When performing tracking servo along a wobble groove of an optical disc (102), an optical pickup (104) is utilized to detect phase differences between a main wobble signal output by receiving the reflected light flux corresponding to the main spot of the optical disc (102) by using a main light reception section (321) of optical detection means (32) and side wobble signals output for the respective side spots by receiving the reflected light fluxes corresponding to the side spots of the optical disc (102) by using a first sub light reception section (322) and a second sub light reception section (323). The difference between the phase differences is calculated by a difference calculation circuit (59) and this difference is used to generate a skew signal including an inclination direction and inclination amount of the optical disc (102).

Description

TECHNICAL FIELD The present invention relates to an optical recording medium (an optical disk such as a DVD-R, a DVD-RW, a DVD + R, a DVD + RW, a CD-R, or a CD-RW). More specifically, the present invention relates to a skew detection method for detecting the inclination (radial skew) of an optical disc and an optical pickup and an optical disc device using the skew detection device. The present invention relates to a skew detection method capable of detecting an inclination of an optical recording medium and an optical pickup and an optical disk device using the skew detection device. This application claims priority on the basis of Japanese Patent Application No. 202-2676771 filed in Japan on September 13, 2002. The application is incorporated herein by reference. 2. Description of the Related Art As the recording density on optical discs increases, the skew margin of optical discs decreases. For this reason, the optical pickup detects the amount of tilt of the optical disk with respect to the optical axis of the optical pickup (objective lens) using a skew sensor, and the optical axis of the objective lens is orthogonal to the signal recording surface of the optical disk according to the amount of tilt. The optical pickup is controlled by a skew servo mechanism. A conventional skew sensor is, for example, as shown in FIG. 1 of Japanese Patent Application Laid-Open No. 9-161691, in which light is applied to a main body portion of an optical pickup toward a signal recording surface of an optical disc. A light-emitting element composed of an LED arranged so as to be reflected, and a two-divided photodiode arranged on the main body of the optical pickup and receiving light reflected on the signal recording surface of the optical disk. When a difference signal corresponding to the amount of tilt of the optical recording medium is extracted from the diode, and this difference signal is detected as a skew signal, In both cases, the skew servo mechanism is controlled by the skew signal so that the optical axis of the optical pickup (the optical axis of the objective lens) is orthogonal to the signal recording surface of the optical recording medium.

The conventional skew sensor as described above requires a light emitting element and a photo diode dedicated to skew detection, so that there is a problem that the number of components increases and the cost of the optical pickup increases.

In addition, since the conventional skew sensor detects the amount of tilt of the optical disk by extracting the difference between the output signals of the two divided photodiodes, if the distance between the optical disk and the skew sensor fluctuates. Even if the tilt amount of the optical disk is the same, the distribution of the light amount of the beam on the photodiode surface for skew detection changes, causing an error in the tilt amount of the optical disk.

In addition, the distance between the optical disk and the skew sensor is always fluctuating because it changes depending on the type of optical disk, such as CD and DVD, the state of chucking of the optical disk to the turntable, and how the optical disk bends. ing. As a result, errors in the output of the photodetector always contain errors, making accurate skew detection difficult. DISCLOSURE OF THE INVENTION Therefore, if skew information can be detected by an optical system for recording / reproducing Z without using a skew sensor having another structure as described above, a skew signal is passed through a lens and a photodetector of an optical system actually used for reading and writing. Can be detected, and accurate skew detection without errors can be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. The purpose of the present invention is to detect the inclination and amount of an optical recording medium by using an optical system for recording and reproducing information on the optical recording medium. Skew detection method and optical pickup and optical disk device using a skew detection device that enable high-accuracy radial skew detection and reduce the number of components to reduce cost It is to provide 2003/011742

(3) A skew detection method according to the present invention is a skew detection method for detecting an inclination of an optical recording medium having a warp group for a light spot guide, wherein a luminous flux from a light source is divided into one main spot and two light spots. The light is separated into side spots and illuminated on the signal recording surface of the optical recording medium. The main spot reflected from the signal recording surface and the reflected light flux corresponding to each of the two side spots are detected by the light detecting means. When tracking servo is performed along the wobble group of the recording medium, a warp signal obtained by receiving the reflected light beam from the main spot and a side spot obtained by receiving the reflected light beam from each side spot Detects the phase error with each woople signal, and generates a skew signal including the tilt direction and tilt amount of the optical recording medium from the difference between the two phase errors. And wherein the door.

Another skew detection method according to the present invention is a skew detection method for detecting an inclination of an optical recording medium having a warp group for an optical spot guide, wherein a luminous flux from a light source is converted into one main spot. And irradiates the signal recording surface of the optical recording medium with the light, and detects the main spot reflected from the signal recording surface and the reflected light flux corresponding to each of the two side spots by the light detecting means. Then, when tracking servo is performed along the wobble group of the optical recording medium, the reflected light flux corresponding to the two side spots is received, so that the light detection means outputs the woofer signal output for each side spot. Detect each phase and apply a phase-locked loop process to each wobble signal to detect the phase error of those wobble signals. And detecting a fluctuation amplitude of the phase error and generating a skew signal including a tilt direction and a tilt amount of the optical recording medium from the difference of the fluctuation amplitude.

Also, an optical pickup according to the present invention includes a light source that emits a light beam for recording or reproduction, a light beam separating unit that separates the light beam from the light source into one main spot and two side spots, and emits the light beam. A focusing means for focusing the main spot and the side spot separated by the separating means and irradiating the optical spot on the optical recording medium; a light flux emitted from the light source to the optical recording medium and a reflected light flux from the optical recording medium; A light separating means for separating light from the main spot and the reflected light flux corresponding to each side spot separated by the light separating means; and a light for a recording / reproducing light flux applied to the optical recording medium. Skew detection device for detecting inclination of optical recording medium with respect to axis Up, the skew detection device performs a tracking servo along the wobble group of the optical recording medium, and receives a reflected light beam corresponding to the main spot when the tracking servo is performed. First and second phase comparing means for receiving a reflected light beam corresponding to each side spot and comparing and detecting a phase error with a wobble signal output from the light detecting means for each side spot, respectively; And a difference calculating means for calculating a difference between the two phase errors output from the second phase comparing means and generating a skew signal including the tilt direction and the tilt amount of the optical recording medium from the difference. I do.

Further, another optical pickup according to the present invention includes a light source that emits a light beam for recording or reproduction, and a light beam separating unit that separates and emits a light beam from the light source into one main spot and two side spots. Focusing means for focusing the main spot and side spot separated by the light beam separating means and irradiating the light spot on the optical recording medium; and a light beam emitted from the light source to the optical recording medium and a light beam from the optical recording medium. A light separating means for separating the reflected light flux, a light detecting means for receiving the reflected light flux corresponding to the main spot and each side spot separated by the light separating means, and a recording / light irradiating optical recording medium. An optical pickup having a skew detection device for detecting an inclination of the optical recording medium with respect to the optical axis of the reproduction light beam, wherein the skew detection device is arranged along a wobble group of the optical recording medium. A first and a second wobble signal detecting means for detecting a warp signal output from the light detecting means for each side spot by receiving reflected light beams corresponding to the two side spots when performing the servoing; A phase locked loop processing is performed on the wobble signals detected by the first and second warp signal detection means to detect phase errors of the wobble signals, thereby detecting a fluctuation amplitude of the phase errors. Calculating a difference between the two phase error amplitudes detected by the first and second amplitude detection means and the first and second amplitude detection means, and generating a skew signal including the tilt direction and the tilt amount of the optical recording medium from the difference; And a difference calculating means.

In addition, the optical disc device according to the present invention includes a driving unit that rotationally drives an optical recording medium, a light source that emits a light beam for recording or reproduction, and a light flux from the light source to one main spot and two side spots. Light beam separating means for separating and emitting light, and light beam separation Focusing means for converging the main spot and side spot separated by the means and irradiating the optical recording medium, and a light flux emitted from the light source to the optical recording medium and a reflected light flux from the optical recording medium. An optical pickup having light separating means for separating light, light detecting means for receiving a main spot separated by the light separating means and a reflected light beam corresponding to each side spot, rotation of an optical recording medium and movement of an optical pickup; Control means for controlling the recording and / or reproducing operation in accordance with the recording and / or reproducing operation; signal processing means for performing signal processing of the recording and Z or reproducing operation on the optical recording medium by the optical pickup; and irradiating the optical recording medium. An optical disc device having a skew detection device for detecting an inclination of the optical recording medium with respect to the optical axis of the recording / reproducing luminous flux, wherein the skew detection device comprises: When tracking servo is performed along the apple group, the wobble signal output from the light detecting means by receiving the reflected light beam corresponding to the main spot and the light beam by receiving the reflected light beam corresponding to each side spot are received. First and second phase comparing means for respectively comparing and detecting a phase error with a wobble signal output for each side spot from the detecting means, and a phase error of both phase errors output from the first and second phase comparing means. And a difference calculating means for calculating a difference and generating a skew signal including a tilt direction and a tilt amount of the optical recording medium from the difference. Further, another optical disc device according to the present invention includes a driving means for rotating and driving an optical recording medium, a light source for emitting a light beam for recording or reproduction, and a light flux from the light source for one main spot and two spots. A light beam separating means for separating the light into light spots and emitting light, a light collecting means for condensing the main spot and the side spots separated by the light beam separating means and irradiating the light to the optical recording medium, and a light emitted from the light source. A light separating means for separating a light beam to the recording medium and a reflected light beam from the optical recording medium; a light detecting means for receiving reflected light beams corresponding to the main spot and each side spot separated by the light separating means; An optical pickup having an optical pickup; control means for controlling rotation of the optical recording medium and movement of the optical pickup in accordance with recording and Z or reproduction operations; An optical disc having signal processing means for performing signal processing of a recording and / or reproducing operation to be performed, and a skew detecting device for detecting an inclination of the optical recording medium with respect to an optical axis of a recording Z reproduction light beam applied to the optical recording medium. The skew detection device is provided along the wobble group of the optical recording medium. And the second obble signal detected by the ブル obble signal detecting means is subjected to phase locked loop processing to detect the phase error of the wobble signal, thereby detecting the fluctuation amplitude of the phase error, thereby detecting the phase error. First and second amplitude detecting means for detecting the fluctuation amplitude of the optical recording medium, and calculating the difference between the two phase error amplitudes detected by the first and second amplitude detecting means, and from the difference, the tilt direction and tilt amount of the optical recording medium. And a difference calculating means for generating a skew signal including the following.

Further objects of the present invention and specific advantages obtained by the present invention will become more apparent from the description of the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of an optical disk device provided with an optical pickup according to the present invention.

FIG. 2 is a configuration diagram of an optical pickup according to the present invention.

FIG. 3 is an explanatory diagram showing the relationship between the wobble group applied to the radial skew detection of the present invention and the main spots and the side spots.

FIG. 4 is a block diagram illustrating a configuration of the skew detection device according to the first embodiment of the present invention.

FIGS. 5A to 5G are explanatory waveform diagrams of a warp signal when a main spot and a side spot in the skew detection device of the present invention track a wobble group on an optical recording medium.

FIG. 6 is a graph showing the relationship between the radial skew and the phase error of the skew detection device according to the first embodiment of the present invention.

FIG. 7 is a block diagram showing a skew detection device according to a second embodiment of the present invention.

FIG. 8A is an explanatory diagram when a warp group applied to radial skew detection according to the second embodiment of the present invention and a main spot and a side spot are shifted by 1/2 track, and FIG. Are the worm group and the main group applied to the radial skew detection according to the second embodiment of the present invention. FIG. 8C is an explanatory view when the pot and the side spot are shifted by 1/4 track (when the spot is narrower than 1/2 track). FIG. 8C is a radial skew according to the second embodiment of the present invention. FIG. 6 is an explanatory diagram when a wobble group applied to one detection is shifted by 3/4 track from a main spot and a side spot (when the width is wider than a 1/2 track).

9A to 9D are graphs showing the relationship between the radial skew and the phase error amplitude of the skew detection device according to the second embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of an optical pickup and an optical disk device using a skew detection method and a skew detection device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a first embodiment of an optical disk device provided with an optical pickup using a skew detecting device according to the present invention, and FIG. 2 is an optical pick-up device having a skew detecting device according to the present invention. FIG. 3 is an explanatory view showing the relationship between a wobble group applied to radial skew detection according to the present invention and a main spot and a side spot. FIG. 4 is a skew detection according to an embodiment of the present invention. FIG. 5 is a block diagram showing the configuration of the device, FIG. 5 is a waveform diagram for explaining a warp signal when a main spot and a side spot in the skew detection device of the present invention track a warp group on an optical recording medium, and FIG. Is a rough graph showing the relationship between the radial skew and the phase error of the skew detection device according to one embodiment of the present invention. The optical disk device shown in FIG. 1 is an example of a recording / reproducing device on which a skew detecting device and an optical pickup described below can be mounted.

First, the configuration of the optical disk device 101 shown in FIG. 1 will be described.

The optical disk device 101 is a driving means for rotating an optical disk 102 which is an optical recording medium such as DVD-R, DVD-RW, DVD + R, DVD + RW, CD-R or CD-RW. Spindle motor 103, an optical pickup 104, and a drive for moving the optical pickup 104 in the radial direction of the optical disc 102. And a feed motor 105 as a moving means.

Here, the spindle motor 103 and the feed motor 105 are controlled based on a command from the system controller 107, and are driven and controlled at a predetermined number of rotations by a -bo control unit 109. Configuration.

The signal modulator / demodulator & ECC block 10.8 shown in Fig. 1 performs signal modulation, demodulation, and addition of ECC (error correction code).

The optical pick-up 104 is a main unit for recording and reproducing the luminous flux from the light source on the signal recording surface of the rotating optical disc 102 in accordance with the command of the signal modulator / demodulator & ECC block 108. It is configured to irradiate separately to two side spots for spotting and tracking. Further, the optical pickup 104 is provided with a light detection means (described later) of the optical pickup 104 in accordance with the reflected light flux corresponding to the main spot and the side spot reflected from the signal recording surface of the optical disk 102. ) Are supplied to the preamplifier 120 and the radial skew signal processing unit 116.

The preamplifier 120 is provided with a focus error signal, a tracking error signal, and a tracking error signal based on various signals output from light detection means (described later) of the optical pickup 104 corresponding to the main spot and the side spot. It is configured to generate RF signals and the like. Also, according to the type of recording medium to be played back, predetermined processing such as demodulation and error correction processing based on these signals is performed by the servo control unit 109, the signal modulator / demodulator & ECC block 108, etc. Is performed.

Here, if the recording signal demodulated by the signal modulator / demodulator & ECC block 108 is for data storage of a computer, for example, it is sent to an external computer 130 or the like via the interface 111. Is done. Thus, the external computer 130 and the like are configured to be able to receive a signal recorded on the optical disk 102 as a reproduction signal.

If the recording signal demodulated by the signal modulator / demodulator & ECC block 108 is for audio-visual use, it is digital-to-analog converted by the DZA conversion section of the DZA, AZD converter 112. Audio. Supplied to visual processing section 113. The audio / visual processing unit 1 1 3 The signal is processed and transmitted to an external imaging / projection device via the audio / visual signal input / output unit 114.

The optical pickup 104 is kneaded with, for example, a feed motor 105 for moving to a predetermined recording track on the optical disk 102. The servo control unit 10 controls the spindle motor 103, controls the feed motor 105, and controls the focusing direction and tracking direction of the dual-axis actuator that holds the objective lens of the optical pickup 104. Done by 9.

Further, the laser control unit 121 controls the laser light source 22 in the optical pickup 104, and is configured to control the output power of the laser light source 22 in the recording mode and the reproduction mode. ing. The laser light source 22 will be described later.

The radial skew signal processing unit 116 performs tracking servo along a signal output from a light detection unit (described later) of the optical pickup 104, that is, a single group formed on the optical disk 102. When the reflected light beam corresponding to the main spot is received, the wobble signal output from the light detecting means is received, and the reflected light beam corresponding to the side spot is received, whereby the light detecting means receives the reflected light beam for each side spot. The skew signal S1 including the tilt direction and the tilt amount of the optical disc 102 is generated from the difference between the two phase errors and the phase error between the two signals.

The skew signal S 1 output from the radial skew signal processing unit 116 is applied to the optical pickup 104 so that its optical axis (the optical axis of the objective lens) is orthogonal to the signal recording surface of the optical disk 102. The skew actuator 117 is configured to be supplied to a skew actuator 117 which is a skew driving means for swinging the skew, and the skew actuator 117 is provided with a skew signal from a radial skew signal processing unit 116. And a skew servo control unit 118 (corresponding to a skew control means described in claims) that is driven and controlled based on the skew. The skew servo control section 118 is configured so as to be able to control also based on a control command from the system controller 107. Next, the configuration of the optical pickup 104 according to the present invention will be described with reference to FIG. The optical pickup 104 is, as shown in FIG. 2, a laser light source 22 for emitting a recording / reproducing light beam, and a collimator arranged in the light beam emitting direction of the laser light source 22 for converting the light beam into parallel light. A lens 24, a grating 26 for separating the parallel light beam into one main spot and two side spots, a beam splitter 28 disposed on the light exit side of the grating 26, and a beam An objective lens (light condensing means) 30 for condensing the light beams of the three spots transmitted through the splitter 28 and irradiating the optical disc 102 with the light, and disposed opposite to the reflection direction of the beam splitter 28; A light detecting means 32 for receiving the reflected light flux from the optical disc 102 separated by the beam splitter 28 and converting the reflected light flux into an electric signal, and these optical components are mounted on a holder body not shown in the figure. Is It has a configuration.

In FIG. 3, the main spot MSP condensed on the signal recording surface of the optical disk 102 is placed on a wool group 102A formed on the optical disk 102, and the two side spots SSP 1. The SSP 2 is spaced a predetermined distance L from the main spot MSP in the T (tangential) direction along the wobble groove 102 A of the optical disc 102 so that the main spot MSP is sandwiched between them. Each of the side spots SSP 1 and SSP 2 is 1/1 in the R (radial) direction crossing the woople group 102 A with respect to the main spot MSP so that the main spot MSP is sandwiched. Two tracks are offset.

Next, the configuration of the radial skew signal processing section 116 including a wobble signal detection photodetector constituting the skew detection apparatus according to the present invention will be described with reference to FIG.

As a photodetector for detecting a wobble signal in the skew detection device, light detection means 32 shown in FIG. 2 used for generating a focus error, a tracking error, and an RF signal is used.

As shown in FIG. 4, the light detecting means 32 receives the reflected light beam from the optical disk 102 corresponding to the main spot MSP, and is formed into a quadrangular light receiving element a, b, c , D, and the first sub-light receiving element e, f divided into two parts in the radial direction for receiving the reflected light beam from the optical disc 102 corresponding to the side spot SSP 1. In correspondence with the light receiving section 3 2 2 and the side spot SSP 2 It comprises a second sub-light-receiving portion 323 composed of light-receiving elements g and h divided in the radial direction and receiving the reflected light beam from the optical disk 102.

As shown in FIG. 4, the radial skew signal processing section 116 includes the respective light receiving elements a and b of the main light receiving section 321, depending on the irradiation area of the reflected light beam 41 corresponding to the main spot MSP. , C, and d, a current-voltage conversion circuit 44 a to 44 d for separately converting the current into a voltage, and a first sub-circuit according to the irradiation area of the reflected light flux 42 corresponding to the side spot SSP 1. Compatible with the current-to-voltage conversion circuit 44 e, 44 ί for each light-receiving element that separately converts the current flowing through each light-receiving element e, f of the light-receiving section 3 22 into a voltage, and the above-mentioned side spot SS 上記 2 Current-to-voltage conversion circuit for each light-receiving element that separately converts the current flowing through each light-receiving element g and h of the second sub-light-receiving section into a voltage according to the irradiation area of the reflected light flux 43 4 h, an addition circuit 45 a for adding the output voltages of the current-voltage conversion circuits 44 a and 44 d, and the current-voltage conversion circuit An addition circuit 45 b for adding the output voltages of the circuits 44 b and 44 c; a subtraction circuit 46 for obtaining a push-pull signal from a difference output between the addition circuits 45 a and 45 b; The difference between the first subtraction circuit 47 for obtaining the push-pull signal (PP signal) from the difference output between the current-voltage conversion circuits 44 e and 44 f, and the current-voltage conversion circuits 44 g and 44 h A second subtraction circuit for obtaining a push-pull signal from the output.

The output side of the subtraction circuit 46 is provided with a push-pull signal at a delay corresponding to the interval L between the main spot MSP and the side spot SSP 1 from the side spot SSP 2 shown in FIG. A circuit 49 and a band-pass filter (BPF) 50 for passing a component of the main wobbled signal s1 from the push-pull signal delayed by the delay circuit 49 are connected in series.

Further, the push-pull signal is supplied to the output side of the subtraction circuit 47 from the side spot SSP 2 shown in FIG. 3 for a time corresponding to twice the interval L between the main spot MSP and the side spot SSP 2. First and second delay circuits 51 and 52 to be delayed, and a BPF (Band Pass Filter) for passing a component of the side wobble signal s 21 from the push-pull signal delayed by the delay circuits 51 and 52 53 are connected in series.

Also, the output side of the subtraction circuit 48 receives a sidewalk from the push-pull signal. BPF (band-pass filter) 54 that passes the digital signal s 22 is connected in series.

In FIG. 4, the output side of a BPF (band-pass filter) 53 detects the phase error by comparing the main wobble signal s 1 and the side wobble signal s 21, and outputs a first signal such as an EX-OR signal. The phase comparison circuit 55 is connected. In addition, the output side of a BPF (bandpass filter) 54 detects a phase error by comparing the main wobble signal s1 and the side wobble signal s22, and a second phase comparison such as EX-OR. Circuit 56 is connected. The phase error detected by the first phase comparison circuit 55 and the first phase comparison circuit 56 is an average phase error amount that changes according to the skew.

A difference calculation circuit 59 is connected to the output side of the first phase comparison circuit 55 and the second phase comparison circuit 56 via LPFs (low-pass filters) 57 and 58. The difference calculation circuit 59 calculates a difference between the phase errors detected by the first phase comparison circuit 55 and the second phase comparison circuit 56, and from the difference, the direction and amount of tilt of the optical disc 102. To generate a skew signal S1 including This skew signal S 1 is output to the skew servo control section 118 as shown in FIG. Next, a skew detection method and operation by the skew detection device according to the first embodiment configured as described above will be described.

The radial skew of the optical disk 102 is detected by using the optical pickup 104 of the optical disk device shown in FIG. That is, the light beam emitted from the laser light source 22 is converted into a parallel light beam by the collimator lens 24, and further separated by the grating 26 into one main spot and two side spots. The light passes through the splitter 28, is condensed by the objective lens 30, and is irradiated on the signal recording surface of the optical disc 102. At this time, as shown in Fig. 3, the main spot MSP of the luminous flux split into three spots is placed on the optical group 102A of the optical disk 102, and the two side spots SSP 1. SSP 2 is offset by 1/2 track in the radial direction across wobble drop 102A.

On the other hand, it corresponds to three spots reflected on the signal recording surface of the optical disc 102. After passing through the objective lens 30, the reflected light flux is reflected by the beam splitter 28, enters the light detecting means 32, and is converted into an electric signal by the light detecting means 32 _c DVD-R, DVD—RW In an optical disk 102 of a standard such as DVD + R, DVD + RW, CD-R or CD-RW, the address information of the optical disk 102 is contained in the form of a wobble address in which a group is wobbled. Also, the mark recorded on the optical disk 102 is recorded at a constant linear velocity (CLV) so that it always has a constant size (length), and the carrier frequency of the wobble address is also constant. 2 Synchronized with the clock frequency of the information (mark) recorded on the top. For this reason, the wobble groove formed on the signal recording surface of the optical disc 102 is also recorded in CLV. Therefore, the wobble period is a fixed length in the optical disk surface, and the adjacent wobble groups are always shifted by a certain phase.

For example, as shown in FIG. 3, between the wobble group 102 A and the wobble groups 102 A 1 and 102 A 2 which are adjacent to the outside and inside of the wobble group 102 A. Are shifted by Δφ + and Δφ-, respectively. The amount of phase shift is the remainder of dividing the length of one round of the wobble group by the wobble cycle for each track.

As described above, since the warp cycle is shifted from track to track, the phases of the warp groups 102 a 1 and 102 a 2 adjacent to the wobble group 102 fluctuate with a certain time period. become. Also, this shift amount (cycle) varies depending on the position in the radial direction.

Here, it is assumed that the optical pickup 104 is controlled by the servo control unit 109 so that tracking is performed in a state where the main spot MSP is arranged in the center of the orb group 112 A shown in FIG. Then, the reflected light flux 41 corresponding to the main spot MSP arranged on the warp group 102 A is incident on the main light receiving section 32 1 of the light detecting means 32, and The reflected light fluxes 42 and 43 corresponding to the side spots SSP 1 and SSP 2 which are half a track away from A are incident on the first and second sub-light receiving sections 3 and 2, respectively. You.

As a result, the current-to-voltage conversion circuit from the light-receiving elements a, b, c, and d The main warp signal s1 obtained through the path 44a44d, the adder circuit 45a45b, the subtractor circuit 46, and the delay circuit 49BPF50 has a waveform as shown in FIG. 5G.

In addition, it can be obtained from each light receiving element ef of the first sub light receiving section 3 2 2 through the current-voltage conversion circuit 4 4 e 4 4 f, the first subtraction circuit 4 7, the delay circuit 5 1 5 2 and the BPF 5 3. The side wobble signal s 21 when the radial rescue Rskew of the optical disc 102 is Rskew = 0 has a waveform as shown in Fig. 5E. 21 has a waveform as shown in FIG. 5D, and the side wobble signal s 21 when the radiano rescue Rskew = — of the optical disc 102 has a waveform as shown in FIG. 5F.

In addition, the radian of the optical disc 102 obtained from each light receiving element gh of the second sub-light receiving section 3 2 3 through the current-to-voltage conversion circuit 44 g 44 h, the second subtraction circuit 48 and the BPF 54 The side wobble signal s22 when the rescue Rskew = 0 has a waveform as shown in Fig. 5E, and the side wobble signal s22 when the radial skew Rskew = + of the optical disc 102 is Fig. 5 The waveform shown in F is shown, and the side wobble signal s 22 at the time of the radian rescue Rskew of the optical disc 102 has the waveform shown in FIG. 5D.

The phase error between the main wobble signal s 1 and the side wobble signal s 21 output from the first phase comparison circuit 55 is shown in FIG. 5B when the radial skew Rskew = 0 of the optical disc 102. The phase error of the optical disc 102 when the radial skew Rskew = + is as shown in FIG. 5A. The phase error of the optical disc 102 when the radial skew Rskew == — is The waveform is as shown in Fig. 5C.

The phase error between the main wobble signal s 1 and the side wobble signal s 21 output from the second phase comparison circuit 56 is as shown in FIG. 5B when the radial skew Rskew of the optical disk 102 is 0. The phase error of the optical disk 102 when the radial skew Rskew = + is as shown in FIG. 5C. The phase error of the optical disk 102 when the radial skew Rskew = — is The waveform is as shown in Fig. 5A. Thus, when wobble is read out by side spots SSP 1 and SSP 2 which are half a rack from the wool group 102 A and shifted from the rack, the phase modulated on both sides of the land is different. . For this reason, when the side spots SSP 1 and SSP 2 are not inclined in the radial direction, the wobble groups 102 A 1 and 102 A 2 of both sides contribute equally, so the push The pull signal is a subtraction of both wobble signals, and the amplitude of the wobble is modulated in a cycle in which the phase difference between the adjacent wobble loops as shown in Fig. 5. Also, when there is a skew in the radial direction, the contribution of the ウォー side warp to the side spots SSP 1 and SSP 2 changes, and as a result, the amplitude modulation degree changes in the push-pull signal, and the warp phase also changes. I do.

For example, if the optical disc 102 is tilted so that the shape of the side spot SSP 1 is deformed in the direction of increasing the strength toward the main spot MPS, the main wobbled component included in the detected wobble signal increases. The amount of phase change is small. When the optical disc 102 is tilted in the opposite direction, the adjacent wobble component increases and the phase change amount increases. At the opposite side spot SSP2, the contribution of the slope is reversed. In other words, if the wobble on the main spot side has a large contribution at one side spot, the contribution of the adjacent woople will be large at the other side spot.

Therefore, the phase of the main wobble signal s1 detected by the push-pull signal of the main spot is compared with the phase of the side warp signals s21 and s22 detected by the side spot to determine the phase with respect to the main wobble. The direction and amount of the radial skew can be determined based on the magnitude of the phase variation by detecting the variation of the phase skew and comparing this with both side spots.

In FIG. 6, a curve 61 shows a change in the output of the phase error with respect to the radial skew Rskew after passing through the LPF 57, and a curve 62 shows a change in the radial skew Rskew after passing through the LPF 58. It shows the output change of the phase error. In this way, the difference between the phase errors detected by the first phase comparison circuit 55 and the second phase comparison circuit 56 of the radial skew signal processing section 116 is calculated by the difference calculation circuit 59, and from this difference, the optical disk 1 0 Generates a skew signal S1 including the tilt direction and tilt amount of 2. The skew signal S 1 is input to the skew servo control unit 118 shown in FIG. 1 to drive and control the skew actuator 117, whereby the optical axis of the optical pickup 104, The optical pickup 104 is operated so that the optical axis of the lens 30 is orthogonal to the signal recording surface of the optical disk 102. That is, by adjusting the entire optical pickup 104 to the inclination of the optical disk 102, the optical axis of the objective lens 30 and the signal recording surface of the optical disk 102 are maintained orthogonal to each other. This prevents a DC offset from occurring in the tracking error signal due to the tilt of the optical pickup 104.

Further, in the optical pickup 104 shown in the above embodiment, recording on an optical disk 102 such as DVD-R, DVD-RW, DVD + R, DVD + RW, CD-R or CD-RW is performed. At the time, a large power beam of about 30 mW is generated from the laser light source 22 which changes according to the recording signal. This light beam is converted into a parallel light beam by a collimator lens 24, and further separated into one main spot and two side spots by a grating 26, then passes through a beam splitter 28, and passes through an objective lens. The light is condensed by 30 and irradiates the signal recording surface of the optical disk 102. As a result, the recording film of the optical disc 102 is altered to record a signal on the optical disc 102.

The reflected light flux reflected from the optical disc 102 is transmitted through the objective lens 30 and then reflected by the beam splitter 28 to be incident on the light detecting means 32. The optical signal received by the main light receiving section 32 1 of the light detecting means 32 is converted into an electric signal by the preamplifier 120 and extracted as a focus error signal. Further, the optical signal received by the first sub-light receiving section 3222 and the first sub-light receiving section 3222 is converted into an electric signal by the preamplifier 120 and extracted as a tracking error signal.

When reproducing an optical disc 102 such as DVD-R, DVD-RW, DVD + R, DVD + RW, CD-R or CD-RW, a laser beam having a constant intensity of about 1 mW is applied to the laser light source 22. This light beam is applied to the optical disk 102 along the same optical path as during recording. Along with this, the reflected light flux reflected from the signal recording surface of the optical disc 102 passes through the objective lens 30, is reflected by the beam splitter 28, and enters the light detecting means 32. Light is received by the main light receiving section 3 2 1 of the light detecting means 3 2 The obtained optical signal is converted into an electric signal by the preamplifier 120 and extracted as an RF signal or a focus error signal. Further, the optical signals received by the first sub-light receiving section 3222 and the second sub-light receiving section 3223 are converted into electric signals by the preamplifier 120, and are taken out as tracking error signals.

According to the skew detection device and the optical pickup 104 and the optical disk device 101 using the skew detection device according to the present embodiment, when tracking servo is performed along the warp group of the optical disk 102. Using the optical pickup 104 for recording / reproduction, the reflected light beam corresponding to the main spot MSP of the optical disk 102 is received by the main light receiving section 321 of the light detecting means 32. And the reflected light beams corresponding to the side spots SSP 1 and SSP 2 of the optical disc 102 are received by the first sub-light receiving section 3 2 2 and the second sub-light receiving section 3 2 3 As a result, the phase error between the side wobble signals s 21 and s 22 output for each side spot is detected, and the difference between the two phase errors is calculated by the difference calculation circuit 59, and from this difference the optical disc is calculated. 1 0 2 Tilt direction and tilt amount Since the skew signal S1 including the skew signal S1 is generated, the radial skew of the optical disc 102 can be detected with high accuracy, and a skew sensor having a different structure as in the related art is not required. In addition, the number of components can be reduced, and the cost of the optical pickup 104 including the skew detection device and the optical disk device 101 can be reduced.

Further, according to this embodiment, the main spot MSP focused on the signal recording surface of the optical disc 102 is arranged on the wobble group '102 A of the optical disc 102, and the two side spots are arranged. G SSP 1 and SSP 2 are separated by a predetermined distance L from the main spot MSP in the tangential direction along the wobble groove 102 A of the optical disc 102 so that the main spot MSP is sandwiched between them. In addition, each side spot SSP 1 and SSP 2 has a 1/2 track in the radial direction across the woofer group 102 A with respect to the main spot MSP so that the main spot MSP is sandwiched between the side spots. Since the optical discs 102 are arranged so as to be shifted from each other, the radial skew of the optical disc 102 can be reliably detected by using the warp group of the optical disc 102, and the skew that does not include an error can be detected. It is possible to output accurately detects the signal. According to this embodiment, the wobble signal is supplied to the signal processing system of the main sample signal s1 corresponding to the main spot MSP and the signal processing system of the side sample signal s21 corresponding to the side spot SSP1. Delay circuits are added to each other, and the delay circuits are configured to match the timing when comparing the main warp signal s1 with the side spots SSP1 and SSP2. It is possible to correct the delay caused by the fact that the spot is separated from the main spot in the tangential direction, and to detect the skew signal with higher accuracy.

Next, a second embodiment of the apparatus using the skew detection method according to the present invention will be described with reference to FIGS.

The skew detection device shown in FIG. 7 is for a case where skew detection is performed only by a signal based on a reflected light beam corresponding to a side spot.

In the second embodiment, the radial skew signal processing unit 116A receives the reflected light beam from the optical disk 102 corresponding to the side spot SSP1 shown in FIG. 3, and is divided into two in the radial direction. The first sub-light receiving section 3 2 2 composed of the light receiving elements e and た, and the light receiving element g that receives the reflected light beam from the optical disk 102 corresponding to the side spot SS Ρ 2 and is divided into two in the radial direction. , H.

In addition, the radial skew signal processing unit 1 16 A is provided with each light receiving element e of the first auxiliary light receiving unit 3 22 according to the irradiation area of the reflected light flux 42 corresponding to the side spot SSP 1 shown in FIG. Current-to-voltage conversion circuits 44 e and 44 f for each light-receiving element that separately convert the current flowing into f to voltage, and the irradiation area of the reflected light flux 43 corresponding to the side spot SSP 2 shown in Fig. 3 Current-to-voltage conversion circuits 44 g, 44 h for each light-receiving element that separately convert the current flowing through each light-receiving element g, of the second sub-light-receiving section 3 23 into a voltage. A first subtraction circuit 47 for obtaining a push-pull signal (PP signal) from the difference output between 44 e and 44 f, and a push-pull signal from the difference output between the current-to-voltage conversion circuit 44 g and 44 h And a second subtraction circuit 48 for determining

Also, on the output side of the first subtraction circuit 47, a BPF (band-pass filter) 53 that passes the component of the push-pull signal from the push-pull signal s21 is connected in series. It is connected.

On the output side of the second subtraction circuit 48, a BPF (band-pass filter) 54 for passing the side pull signal s22 from the push-pull signal is connected in series.

In FIG. 7, a PLL 70 that detects a phase error by performing a phase 'locked' loop process on the side wobble signal s 21 is connected to the output side of the BPF (bandpass filter) 53. Further, a first amplitude detection circuit 71 for detecting the phase error amplitude output from the PLL 70 is connected to the output side of the PLL 70. The amplitude of this phase error changes depending on the tilt direction of the optical disc 102. The output side of the BPF (bandpass filter) 54 is connected to a PLL 72 that detects a phase error by performing a phase-locked loop process on the side worm signal s 22. A second amplitude detection circuit 73 for detecting the phase error amplitude output from the PLL 72 is connected to the output side of the second. The amplitude of the phase error changes depending on the tilt direction of the optical disk 102.

The difference calculation circuit 74 shown in FIG. 7 calculates the difference between the two phase error amplitudes detected by the first amplitude detection circuit 71 and the second amplitude detection circuit 73, and from the difference, the tilt direction of the optical disc 102. And a skew signal S2 including the amount of inclination. This skew signal S2 is output to the skew servo control unit 118 as shown in FIG.

In such a skew detection device according to the second embodiment, the two side spots SSP1 and SSP2 are mounted on the optical disc 102 with respect to the main spot MSP so that the main spot MSP is sandwiched therebetween. They are arranged at a predetermined distance L in the tangential direction along the warp group 102A. The difference between the second embodiment and the first embodiment is that the main spot MSP is sandwiched in the radial direction crossing the waple tube 102A from the main spot MSP, and The point is that the distance from P to each side spot SSP 1 and SSP 2 is not the same.

For example, as shown in Fig. 8, each side spot SPT 1 and SPT 2 are narrower (Fig. 8B) and wider than the main track MSP by a half track (Fig. 8A). Position (Figure 8C). In the skew detection device in such a state, the reflected light fluxes 42 and 43 corresponding to the side spots SSP 1 and SSP 2 respectively include the first sub-light receiving portion 3 22 and the second sub-light receiving portion.

It is incident on 3 2 3.

As a result, the current-to-voltage conversion circuit is

4 4 e, 44 f, side wobble signal s 21 of optical disk 102, obtained through first subtraction circuit 47 and 8 to 53, is phase-locked processed by PLL 70 As a result, the phase error is detected, and the first error detection circuit 71 detects the phase error amplitude. Also, the side wobble of the optical disc 102 obtained from the light receiving elements g and h of the second sub-light receiving section 3 2 3 through the current-to-voltage conversion circuits 44 g and 44 h through the second subtraction circuit 48 and the BPF 54 The phase error is detected by subjecting the signal s 22 to phase lock-loop processing by the PLL 72, and the phase error amplitude is detected by the second amplitude detection circuit 73.

The amplitude of these phase errors changes depending on the tilt direction of the optical disc 102. Therefore, if the radial displacement of the side spots SSP 1 and SPP 2 with respect to the wobble group 102 A is made wider than 1/2 track, as shown in Figure 8C, for example, The relationship between the skew and the phase error amplitude has characteristics as shown in FIGS. 9A and 9B. The reason for such characteristics will be described below. In Fig. 8C, when the radial skew is in the + (plus) direction, the deviation of the center of gravity of the spot and the deviation of the spot position from the 1/2 track are canceled out at the position of the side spot SSP1. The contributions from the warp track are equal. Therefore, the phase error amplitude detected by the first amplitude detection circuit 71 becomes maximum as shown in FIG. 9A. Therefore, the position of the side spot SSP 1 is suitable for skew detection. In addition, at the position of the side spot SSP2, the contribution of the single track on one side becomes large, which is not suitable for skew detection. Also, in Fig. 8C, when the radial skew is in one (negative) direction, at the position of the side spot SSP2, the shift of the center of gravity of the spot and the shift of the spot position from the 1/2 track cancel each other out. The contribution from the truck is equal. Therefore, the phase error amplitude detected by the second amplitude detection circuit 73 becomes the maximum as shown in FIG. 9B. Therefore, the position of the side spot SSP 2 is 1742

21 Suitable for detection. In addition, at the position of the side spot SSP1, the contribution of the warp track on one side is large, and is not suitable for skew detection.

Also, the radial skew and phase error when the radial displacement of the side spots SSP 1 and SSP 2 with respect to the warp group 102 A is narrower than the 1/2 track deviation (Fig. 8B). The relationship with the amplitude has characteristics as shown in FIGS. 9C and 9D. The reason for such a characteristic will be described below.

In Fig. 8B, when the radial skew is in one direction, at the position of the side spot SSP1, the deviation of the center of gravity of the spot and the deviation of the spot position from the 1Z2 track cancel each other, and the contribution from the wobble track Are equal. Therefore, the phase error amplitude detected by the first amplitude detection circuit 71 becomes the maximum as shown in FIG. 9C. Therefore, the position of the side spot S SP 1 is suitable for skew detection. At the position of the side spot S SP 2, the contribution of the wobble track on one side increases, and is not suitable for skew detection.

Also, as shown in Figure 8B, when the radial skew is in the + direction, at the position of the side spot SSP 2, the deviation of the center of gravity of the spot and the deviation of the spot position from the 1-2 track The contributions from the wobble tracks are equalized. Therefore, the phase error amplitude detected by the second amplitude detection circuit 73 becomes maximum as shown in FIG. 9D. Therefore, the position of the side spot S SP 2 is suitable for skew detection. Note that, at the position of the side spot SSP1, the contribution of the wobbled track on one side is large, and is not suitable for skew detection.

Therefore, as shown in FIGS. 9A to 9D, since the characteristics are different depending on the positions of the side spots SSP1 and SSP2 and the direction of the radial skew, the difference between the two phase error amplitudes is calculated within the range of the dotted line. The skew signal S2 including the tilt direction and the tilt amount of the optical disc 102 can be generated from the difference calculated by the circuit 74.

In the second embodiment, the same effects as those of the above-described embodiment can be obtained, and the circuit configuration of the skew detection device can be simplified as compared with the case of the above-described embodiment. Further, as described in the first embodiment and the second embodiment, the radial skew signal processing section 116 for detecting the radial skew signal may be provided on the optical pickup 104 side. However, it may be provided on the optical disk device 101 side.

Further, the present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications, substitutions, or equivalents thereof may be made without departing from the scope of the appended claims and the gist thereof. It will be apparent to those skilled in the art that INDUSTRIAL APPLICABILITY As described in detail above, according to the skew detection method and the optical pickup using the skew detection device and the optical disk device according to the present invention, the optical system for recording and reproducing Z on an optical recording medium The skew sensor is configured to be able to detect the tilt and the amount of the optical recording medium by utilizing the skew sensor. This eliminates the need for components and reduces the number of components, thereby reducing the cost of the optical pickup and optical disk device including the skew detection device.

Claims

The scope of the claims

1. A skew detection method for detecting an inclination of an optical recording medium having a wobble group for a light spot guide,

The light beam from the light source is split into one main spot and two side spots, and irradiates the signal recording surface of the optical recording medium.The main spot and two side spots reflected from the signal recording surface in the previous period The reflected light flux corresponding to each of is detected by the light detection means,

When tracking servo is performed along a wobble group of the optical recording medium, a wobble signal obtained by receiving a reflected light beam from the main spot and a size obtained by receiving a reflected light beam from each of the side spots. Phase error with the wobble signal for each spot

A skew detection method comprising: generating a skew signal including a tilt direction and a tilt amount of the optical recording medium from a difference between the two phase errors.

2. Each of the side spots is spaced apart from the main spot by a predetermined distance in a tangential direction along a wobble group of the optical recording medium so that the main spot is sandwiched between the side spots. And the side spots are offset from the main spot by 1Z2 tracks in the radial direction across the wobbled loop so that the main spot is sandwiched between the side spots. 2. The skew detection method according to claim 1, wherein:

3. The skew detection method according to claim 1, wherein the detected phase error is an average phase error amount.

4. The skew detection method according to claim 1, wherein the detected phase error is a magnitude of a phase change amount due to a period shift of an adjacent wobble group.

5. A skew detection method for detecting an inclination of an optical recording medium having a wobble group for a light spot guide,

The luminous flux from the light source is split into one main spot and two side spots, and irradiates the signal recording surface of the optical recording medium. The reflected light flux corresponding to each of the spot and the two side spots is detected by the light detecting means,

When tracking servo is performed along the warp group of the optical recording medium, by receiving reflected luminous fluxes corresponding to the two side spots, the light detection unit outputs a warp signal output for each side spot, respectively. Detecting and performing phase 'locked' loop processing on each of the wobble signals to detect the phase error of the orbnorre signal, thereby detecting the fluctuation amplitude of the phase error,

A skew detection method, wherein a skew signal including a tilt direction and a tilt amount of the optical recording medium is generated from the difference between the fluctuation amplitudes.

6. The side spots are spaced apart from each other by a predetermined distance in the tangential direction along the wobble groove of the optical recording medium with respect to the main spot so that the main spot is sandwiched therebetween. At the same time, the main spot is sandwiched in the radial direction crossing the warp group from the main spot, and the amount of displacement in the radial direction crossing the warp group is not 12 tracks. 6. The skew detection method according to claim 5, wherein:

7. A light source for emitting a recording or reproducing light beam,

Light beam separating means for separating the light beam from the light source into one main spot and two side spots and emitting the light beam;

Focusing means for focusing the main spot and side spot separated by the light beam separating means, respectively, and irradiating the light spot on an optical recording medium;

Light separating means for separating a light beam emitted from the light source to the optical recording medium and a reflected light beam from the optical recording medium,

Light detecting means for receiving reflected light beams corresponding to the main spot and each of the side spots separated by the light separating means;

A skew detection device for detecting an inclination of the optical recording medium with respect to an optical axis of a recording / reproducing light beam applied to the optical recording medium,

The skew detection device,

When performing tracking servo along the warp group of the optical recording medium, The wobble signal output from the light detecting means by receiving the reflected light beam corresponding to the main spot, and the side spot from the light detecting means by receiving the reflected light beam corresponding to each of the side spots. First and second phase comparing means for comparing and detecting a phase error with a sample signal output every time, and calculating a difference between both phase errors output from the first and second phase comparing means, respectively. And a difference calculating means for generating a skew signal including a tilt direction and a tilt amount of the optical recording medium from the difference.

8. The side spots are spaced apart from each other by a predetermined distance in a tangential direction along the wobble group of the optical recording medium with respect to the main spot so that the main spot is sandwiched between the side spots. The main spot is sandwiched in the radial direction crossing the wobble group from the main spot, and the displacement in the radial direction crossing the warp group is 12 tracks. 8. The optical pickup according to claim 7, wherein:

9. The optical pickup according to claim 7, wherein the detected phase error is an average phase error amount.

10. The optical pickup according to claim 7, wherein the detected phase error is a magnitude of a phase fluctuation amount due to a period shift of an adjacent wobble group.

11. A delay circuit for delaying the wobbled signal is added to the signal processing system for the wobble signal corresponding to the main spot and the signal processing system for the wobbled signal corresponding to the side spot, respectively. 8. The optical pickup according to claim 7, wherein timings for comparing and detecting the wobble signals corresponding to the main spot and the respective side spots are matched.

1 2. A light source for emitting a recording or reproducing light beam,

The main spot and the side spots separated by the light beam separating means are respectively Focusing means for focusing and irradiating the optical recording medium with light;

Light detection means for receiving reflected light beams corresponding to the main spot and each side spot separated by the light separation means,

A skew detection device that detects an inclination of the optical recording medium with respect to an optical axis of a recording Z reproduction light beam applied to the optical recording medium,

The skew detection device,

When tracking servo is performed along the warp group of the optical recording medium, by receiving reflected light fluxes corresponding to the two side spots, the warp signals output from the light detection means for each side spot are respectively received. First and second warp signal detection means for detecting;

The wobble signal detected by the first and second wobble signal detection means is subjected to phase locked loop processing to detect a phase error of the wobble signal, thereby detecting a fluctuation amplitude of the phase error. First and second amplitude detection means,

A difference calculating unit that calculates a difference between the two phase error amplitudes detected by the first and second amplitude detecting units and generates a skew signal including the tilt direction and the tilt amount of the optical recording medium from the difference. An optical pickup, comprising:

13. The side spots are spaced apart from the main spot by a predetermined distance in the tangential direction along the wobble group of the optical recording medium so that the main spot is sandwiched therebetween. At the same time, the side spots are located at positions where the amount of displacement when arranged in the radial direction crossing the warp group with respect to the main spot so as to sandwich the main spot is not a 1Z2 track. 13. The optical pickup according to claim 12, wherein the optical pickup is arranged.

1 4. Driving means for rotating the optical recording medium,

A light source that emits a light beam for recording or reproduction, a light beam separating unit that separates and emits a light beam from the light source into one main spot and two side spots, and a light beam separating unit that separates the light beam from the light source. Light condensing means for condensing the main spot and the side spots and irradiating the light to the optical recording medium; and light emitted from the light source to the optical recording medium. Light separating means for separating the light flux and the reflected light flux from the optical recording medium; and light detecting means for receiving the reflected light flux corresponding to the main spot and each of the side spots separated by the light separating means. An optical pickup having

Control means for controlling the rotation of the optical recording medium and the movement of the optical pickup in accordance with a recording and / or reproducing operation;

Signal processing means for performing signal processing of a recording and / or reproducing operation on the optical recording medium by the optical pickup; and an inclination of the optical recording medium with respect to an optical axis of a recording / reproducing light beam applied to the optical recording medium. An optical disc device having a skew detection device for detecting

The skew detection device,

When tracking servo is performed along the warp group of the optical recording medium, a warp signal output from the light detecting means by receiving a reflected light beam corresponding to the main spot, and corresponding to each side spot First and second phase comparing means for comparing and detecting a phase error with a wobble signal output from the light detecting means for each side spot by receiving the reflected light flux, and the first and second phase comparing means, respectively. An optical disc device, comprising: a difference calculating unit that calculates a difference between the two phase errors output from the two-phase comparing unit and generates a skew signal including the tilt direction and the tilt amount of the optical recording medium from the difference. .

15. Each of the side spots is spaced apart from the main spot by a predetermined distance in the tangential direction along the wobble group of the optical recording medium so as to sandwich the main spot. Claims characterized in that the side spots are displaced from the main spot by 1 Z 2 tracks in a radial direction crossing the oval group so as to sandwich the main spot. Item 15. The optical disk device according to item 14.

16. The optical disk device according to claim 14, wherein the detected phase error is an average phase error amount.

17. The optical disk device according to claim 14, wherein the detected phase error is a magnitude of a phase fluctuation amount due to a period shift of an adjacent warp.

1 8. Signal processing system and side of the warp signal corresponding to the main spot A delay circuit for delaying a wobble signal is added to a signal processing system of a wobble signal corresponding to a spot, and a delay circuit for comparing and detecting the main spot with the woople signal corresponding to each of the side spots by the delay circuit. 18. The optical disc device according to claim 17, wherein timing is adjusted.

1 9. Driving means for rotationally driving the optical recording medium,

A light source that emits a light beam for recording or reproduction, a light beam separating unit that separates and emits a light beam from the light source into one main spot and two side spots, and the light beam separated by the light beam separating unit. A light condensing means for converging a main spot and a side spot to irradiate an optical recording medium; and separating a light flux emitted from the light source to the optical recording medium and a reflected light flux from the optical recording medium. An optical pickup comprising: a light separating unit; and a light detecting unit that receives a reflected light beam corresponding to the main spot and the side spots separated by the light separating unit.

Control means for controlling rotation of the optical recording medium and movement of the optical pickup in accordance with recording and Z or reproduction operations;

A signal processing means for performing signal processing for recording and / or reproducing operations on the optical recording medium by the optical pickup; and an inclination of the optical recording medium with respect to an optical axis of a recording / reproducing light beam applied to the optical recording medium. An optical disc device having a skew detection device for detecting

The skew detection device,

When tracking servo is performed along the wobble group of the optical recording medium, a phase-locked loop process is performed on the wobble signal detected by the first and second wobble signal detection means, and the wobble signal is processed. First and second amplitude detecting means for detecting a phase error and detecting a fluctuation amplitude of the phase error by detecting a fluctuation amplitude of the phase error;

A difference calculating unit that calculates a difference between the two phase error amplitudes detected by the first and second amplitude detecting units and generates a skew signal including the tilt direction and the tilt amount of the optical recording medium from the difference. An optical disk device comprising:

20. Each of the side spots is connected to the main spot so that the main spot is sandwiched. The optical recording medium is spaced apart from the spot by a predetermined distance in a tangential direction along the wobbled groove of the optical recording medium, and the side spots are attached to the main spot so that the main spot is sandwiched therebetween. 20. The optical disc device _{c according} to claim 19, wherein a displacement amount in a radial direction crossing the wobble group is arranged at a position other than 1Z2 track.